[U-Boot] [PATCH v1] usb: gadget: f_dfu: write req->actual bytes
From: Felipe Balbi felipe.balbi@linux.intel.com
If last packet is short, we shouldn't write req->length bytes to non-volatile media, we should write only what's available to us, which is held in req->actual.
Signed-off-by: Felipe Balbi felipe.balbi@linux.intel.com Signed-off-by: Andy Shevchenko andriy.shevchenko@linux.intel.com --- drivers/usb/gadget/f_dfu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/f_dfu.c b/drivers/usb/gadget/f_dfu.c index 8e7c981657..64cdfa7c98 100644 --- a/drivers/usb/gadget/f_dfu.c +++ b/drivers/usb/gadget/f_dfu.c @@ -159,7 +159,7 @@ static void dnload_request_complete(struct usb_ep *ep, struct usb_request *req) int ret;
ret = dfu_write(dfu_get_entity(f_dfu->altsetting), req->buf, - req->length, f_dfu->blk_seq_num); + req->actual, f_dfu->blk_seq_num); if (ret) { f_dfu->dfu_status = DFU_STATUS_errUNKNOWN; f_dfu->dfu_state = DFU_STATE_dfuERROR;
On 02/10/2017 05:32 PM, Andy Shevchenko wrote:
From: Felipe Balbi felipe.balbi@linux.intel.com
If last packet is short, we shouldn't write req->length bytes to non-volatile media, we should write only what's available to us, which is held in req->actual.
Signed-off-by: Felipe Balbi felipe.balbi@linux.intel.com Signed-off-by: Andy Shevchenko andriy.shevchenko@linux.intel.com
Since I have no clue about DFU internals, I will wait for Lukasz's Ack.
drivers/usb/gadget/f_dfu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/f_dfu.c b/drivers/usb/gadget/f_dfu.c index 8e7c981657..64cdfa7c98 100644 --- a/drivers/usb/gadget/f_dfu.c +++ b/drivers/usb/gadget/f_dfu.c @@ -159,7 +159,7 @@ static void dnload_request_complete(struct usb_ep *ep, struct usb_request *req) int ret;
ret = dfu_write(dfu_get_entity(f_dfu->altsetting), req->buf,
req->length, f_dfu->blk_seq_num);
req->actual, f_dfu->blk_seq_num);
Hi,
Marek Vasut marex@denx.de writes:
On 02/10/2017 05:32 PM, Andy Shevchenko wrote:
From: Felipe Balbi felipe.balbi@linux.intel.com
If last packet is short, we shouldn't write req->length bytes to non-volatile media, we should write only what's available to us, which is held in req->actual.
Signed-off-by: Felipe Balbi felipe.balbi@linux.intel.com Signed-off-by: Andy Shevchenko andriy.shevchenko@linux.intel.com
Since I have no clue about DFU internals, I will wait for Lukasz's Ack.
you don't need to have any clues about DFU internals to realise that this fixes an actual bug, see below:
drivers/usb/gadget/f_dfu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/f_dfu.c b/drivers/usb/gadget/f_dfu.c index 8e7c981657..64cdfa7c98 100644 --- a/drivers/usb/gadget/f_dfu.c +++ b/drivers/usb/gadget/f_dfu.c @@ -159,7 +159,7 @@ static void dnload_request_complete(struct usb_ep *ep, struct usb_request *req) int ret;
ret = dfu_write(dfu_get_entity(f_dfu->altsetting), req->buf,
req->length, f_dfu->blk_seq_num);
req->actual, f_dfu->blk_seq_num);
DFU driver queues a request to USB controller. Per the gadget API req->length contains maximum amount of data to be transmitted. req->actual is written by USB controller with the actual amount of data that we transmitted.
In the case of IN (TX), upon completion req->length and req->actual should always be equal (unless errors show up, etc)
In the case of OUT (RX), upon completion req->actual MAY BE less than req->length and that's not an error. Say host sent us a short packet which causes early termination of transfer.
With that in mind, let's consider the situation where we're receiving data from host using DFU. Let's assume that we have a 4096 byte buffer for transfers and we're receiving a binary that's 7679 bytes in size.
Here's what we will do (pseudo-code):
int remaining = 7679; char buf[4096];
while (remaining) { req->length = 4096; req->buf = buf; usb_ep_queue(req);
/* wait for completion */
remaining -= req->actual;
dfu_write(buf, req->length); /* this is the error */ }
Can you see here that in the last packet we will write 4096 bytes when we should write only 3583?
participants (3)
-
Andy Shevchenko -
Felipe Balbi -
Marek Vasut